The intrinsic safety of a technical system is a property which ensures, for example, by means of or due to special principles of construction that an unsafe state does not occur even in the case of a fault in the technical system. This can be achieved by various different measures so that the risk of a dangerous situation occurring is minimised as far as possible. In general, a fault can be described as a situation in which there is a risk or the danger that a risk may occur. In particular and by way of example, such a risk can be defined as the possibility of producing a spark when closing an electric circuit in areas where there is a risk of explosion.
An intrinsically safe circuit generally consists of a power supply, a driver circuit, and an electric device. The driver circuit is supplied with electric power by the power supply and generates a control signal and/or a power supply signal and transmits said signal to the electric device.
Electronic devices and apparatuses in intrinsically safe circuits, in particular during their use or intended use in atmospheres or environments that are at risk of explosion, can be limited in their power consumption by resistors in the supply line in order to avoid the formation of an ignitable spark, so that there is absolutely no risk of an explosion occurring.
In many electronic systems, AC voltage signals are used to modulate a signal and transmit said signal to an electric device. For decoupling (in particular for DC decoupling) the AC voltage signals capacitors can be used (so-called coupling capacitors). In this case, however, it has to be ensured that the power stored in the capacitor is not dissipated in any way in the case of a fault (e.g., with the sudden discharge of the capacitor) such that an ignitable spark is formed.